Wind power generator equipped with a cooling system

ABSTRACT

A wind power generator has a nacelle; a hub rotatable about an axis of rotation with respect to the nacelle; at least two blades fitted to the hub; an electric machine which is fitted to the nacelle, is bounded by an inner surface extending about the axis of rotation, and has a rotor and a stator; and a cooling system for airflow cooling the electric machine, and which has a deflector body for defining a gap between the deflector body and the electric machine and guiding the airflow into the gap.

PRIORITY CLAIM

This application claims the benefit of and priority to Italian Patent Application No. MI2008A 001122, filed on Jun. 19, 2008, the entire contents of which are incorporated herein.

BACKGROUND

Known airflow cooling systems are not particularly efficient, especially in the case of generators equipped with a cylindrical electric machine.

SUMMARY

The present invention relates to a wind power generator equipped with a cooling system.

More specifically, the present invention relates to a wind power generator comprising a nacelle; a hub rotatable about an axis of rotation with respect to the nacelle; at least two blades fitted to the hub; an electric machine which is fitted to the nacelle, is bounded by an inner surface extending about the axis of rotation, and has a rotor and a stator; and a cooling system for airflow cooling the electric machine.

It is an object of the present invention to provide a wind power generator equipped with a highly efficient cooling system.

A further object of the present invention is to provide a wind power generator equipped with a straightforward, low-cost cooling system.

According to one embodiment of the present invention, there is provided a wind power generator equipped with a cooling system, the wind power generator comprising a nacelle; a hub rotatable about an axis of rotation with respect to the nacelle; at least two blades fitted to the hub; an electric machine which is fitted to the nacelle, is bounded by an inner surface extending about the axis of rotation, and has a rotor and a stator; and a cooling system for airflow cooling the electric machine, and which comprises a deflector body for defining a gap between the deflector body and the electric machine and guiding the airflow into the gap.

According to the present invention, the efficiency of the cooling system is improved by the entire airflow being forced into the gap, which runs close to the electric machine and improves thermal exchange by preventing part of the airflow from flowing too far away from the hottest parts of the electric machine.

Additional features and advantages are described in, and will be apparent from, the following Detailed Description and the figures.

BRIEF DESCRIPTION OF THE DRAWINGS

A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which:

FIG. 1 shows a partly sectioned side view, with parts removed for clarity, of a wind power generator in accordance with the present invention;

FIG. 2 shows a larger-scale lateral section of a detail of the FIG. 1 wind power generator;

FIG. 3 shows a larger-scale view in perspective, with parts removed for clarity, of a detail of the FIG. 1 wind power generator;

FIG. 4 shows a larger-scale lateral section of a detail of the FIG. 1 wind power generator.

DETAILED DESCRIPTION

Number 1 in FIG. 1 indicates as a whole a wind power generator, which comprises a pylon 2 extending along a vertical axis A1; a nacelle 3 fitted to the top end of pylon 2 and rotatable with respect to pylon 2 about axis A1; a hub 4 mounted to rotate with respect to nacelle 3 about an axis of rotation A2 crosswise to axis A1; and three blades 5, only two of which are shown by dash lines in FIG. 1.

Pylon 2 is substantially defined by a hollow cylinder housing stairs (not shown in the drawings) and/or lifts (not shown in the drawings).

Pylon 2 is normally secured to the ground by a foundation (not shown in the drawings). Alternatively, in off-shore systems, pylon 2 is secured to a floating platform (not shown in the drawings).

Nacelle 3 comprises a hollow body fitted to the top end of pylon 2 to rotate about axis A1, and supports an electric machine 6 having a rotor 8 and a stator 9, and bounded by an inner surface 7 extending about axis of rotation A2. In other words, electric machine 6 is a hollow cylindrical generator.

Likewise, hub 4 comprises a hollow body integral with rotor 8.

Wind power generator 1 comprises a cooling system 10 supported partly by hub 4 and partly by nacelle 3, and which serves to airflow cool electric machine 6, and in particular to conduct an airflow, predominantly in a direction D1 parallel to axis of rotation A2, from an inlet 11 in hub 4 to an outlet 12 in nacelle 3.

In the example shown in the drawings, stator 9 extends about rotor 8, and rotor 8 is integral with hub 4 and extends inside stator 9. The inner surface 7 of electric machine 6 is therefore the inner surface of rotor 8.

Stator 9 is fixed or connected directly to nacelle 3 along an inner cylindrical surface of nacelle 3. Hub 4 and rotor 8 are connected to each other and supported by a bearing 13 in turn supported by nacelle 3.

In a variation not shown in the drawings, the rotor extends about the stator, the stator is located inside the rotor, and the inner surface of the electric machine is defined by the stator.

Cooling system 10 comprises, in succession from inlet 11 to outlet 12, an air intake filtration device 14; a ventilation unit 15; and a deflector body 16.

With reference to FIG. 4, filtration device 14 is fitted to hub 4, is located at inlet 11, and comprises a convex panel 17 located in front of inlet 11 and having an outward-facing convex face 18 and an oppositely-convex annular edge 19; an annular panel 20 having a concave face 21 extending about edge 19 and facing convex panel 17; and an annular panel 22 extending inside convex panel 17 and comprising a convex face 23 facing convex panel 17, and a concave face 24 facing hub 4.

Panel 17 is fitted to hub 4 by spacer arms 25, whereas panels 20 and 22 are fixed or connected directly to hub 4 about inlet 11. Panels 17, 20 and 22 are guide panels for guiding the air intake into hub 4, and are designed and positioned with respect to one another to define a labyrinth air intake path. Filtration device 14 thus prevents, or at least reduces, entry of water, snow or impurities into hub 4 and nacelle 3.

With reference to FIG. 1, ventilation unit 15 is housed inside hub 4, and comprises a powered fan 26; a guide 27 parallel to axis of rotation A2; and a slide 28 that runs along guide 27 in direction D1, and supports fan 26.

Guide 27 comprises two rails 29 located about axis of rotation A2 and extending in direction Dl. Fan 26 serves to increase airflow speed in direction D1 into nacelle 3.

Deflector body 16 serves to form a gap 30 between deflector body 16 itself and electric machine 6, and to guide the airflow into gap 30.

As shown more clearly in FIG. 2, deflector body 16 is fixed or connected to electric machine 6, in particular to rotor 8, by means of brackets 31.

In the example shown in the drawings, and particularly in FIG. 1, rotor 8 comprises a sleeve 32 supported by bearing 13 and integral with hub 4; a cylindrical structure 33 integral with sleeve 32; and permanent magnets 34 fixed along the outer surface of cylindrical structure 33. Cylindrical structure 33 defines inner surface 7, which is a cylindrical surface.

Cooling system 10 also comprises fins 35 parallel to direction D1 and fixed or connected to inner surface 7 of cylindrical structure 33.

Stator 9 comprises a stator pack 36 fixed or connected to the surface of nacelle 3; and stator windings (not shown in the drawings).

With reference to FIG. 2, deflector body 16 is substantially axially symmetrical about axis of rotation A2, is fixed or connected to sleeve 32 by brackets 31, and comprises a substantially conical central portion 37 for guiding the airflow to inner surface 7 and defined by a central panel 38 and by a number of panels 39 extending about central panel 38; and a cylindrical portion 40 facing and parallel to inner surface 7, and which serves to define gap 30 and comprises a number of panels 41. Panels 38, 39 and 41 are connected removably to one another.

With reference to FIG. 3, fins 35 extend from inner surface 7 of rotor 8 towards axis of rotation A2, and are divided into groups 42 and 43, each of which, in addition to a given number of fins 35, comprises a perforated cylindrical sector 44 fixed by screws to cylindrical structure 33. As shown in FIG. 3, fins 35 and respective cylindrical sector 44 are preferably formed in one piece.

With reference to FIG. 2, panel 38 is fixed or connected to panels 39 by means of thumbscrews 45, and comprises grips 46 by which to remove panel 38 easily to allow access by maintenance personnel inside hub 4.

With reference to FIG. 1, fan 26 is movable along axis of rotation A2 to allow passage by maintenance personnel and also to set the fan to the best operating position.

Cooling system 10 also extends partly outside nacelle 3, and comprises fins 47 parallel to axis of rotation A2 and fixed or connected to the outer surface of nacelle 3, at stator 9, to assist cooling stator 9.

In actual use, nacelle 3 is oriented about axis A1 so that axis of rotation A2 is positioned in the wind direction, with blades 5 into the wind, and the airflow therefore flows naturally along the labyrinth path into inlet 11, through hub 4 and nacelle 3, and out through outlet 12. At the same time, part of the air flows over the outer surface of nacelle 3 and onto fins 47, which increase the air-stator 9 heat exchange surface.

Airflow inside hub 4 and nacelle 3 is also assisted by fan 26, which serves to overcome any load losses in the airflow, and increases airflow speed inside hub 4 and nacelle 3.

The airflow is diverted by deflector body 16, and assumes first a predominantly radial and then a purely axial speed component, both with reference to axis of rotation A2. That is, portion 37 serves to guide the airflow to inner surface 7 of electric machine 6, and portion 40 of deflector body 16 to guide and keep the airflow close to inner surface 7 of electric machine 6 and fins 35, so the entire airflow inside nacelle 3 contacts the hottest parts of electric machine 6.

It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present subject matter and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims. 

The invention is claimed as follows:
 1. A wind power generator comprising: a nacelle; a hub rotatable about an axis of rotation with respect to the nacelle; at least two blades connected to the hub; a hollow electric machine connected to the nacelle and located inside the nacelle, the hollow electric machine bounded by an inner surface extending about the axis of rotation and having a rotor and a stator; and a cooling system configured to direct airflow from an inlet in the hub to an outlet in the nacelle to cool the hollow electric machine, the cooling system including a deflector body at least partly housed in the hollow electric machine and including a substantially conical central portion configured to guide the airflow to the inner surface of the hollow electric machine, and an end portion which defines a gap between the deflector body and the inner surface of the hollow electric machine, the substantially conical central portion configured to guide the airflow into the gap.
 2. The wind power generator of claim 1, wherein the deflector body is connected to the hollow electric machine.
 3. The wind power generator of claim 1, wherein the stator extends about the rotor and the deflector body is connected to the rotor.
 4. The wind power generator of claim 1, wherein the deflector body includes a number of panels assembled to one another, at least one of said panels configured to be removed.
 5. The wind power generator of claim 1, wherein the cooling system includes a plurality of cooling fins connected to the hollow electric machine along the inner surface.
 6. The wind power generator of claim 5, wherein each fin extends parallel to the axis of rotation and towards the axis of rotation.
 7. The wind power generator of claim 5, wherein the fins are divided into a plurality of groups of fins, each group of fins including a respective cylindrical sector connected to the hollow electric machine along the inner surface.
 8. The wind power generator of claim 1, wherein the cooling system includes a ventilation unit configured to conduct the airflow from the hub to the nacelle.
 9. The wind power generator of claim 8, wherein the ventilation unit is housed in the hub.
 10. The wind power generator of claim 8, wherein the ventilation unit includes a fan movable between a work position and a rest position and configured to enable passage into the hub.
 11. The wind power generator of claim 8, wherein the ventilation unit includes a fan, a guide, and a slide, the fan is connected to the slide, which is movable selectively along the guide.
 12. The wind power generator of claim 1, wherein the cooling system includes a filtration device located in front of the inlet, said filtration device configured to prevent unwanted material from entering the hub.
 13. The wind power generator of claim 12, wherein the filtration device includes a plurality of guide panels positioned with respect to one another to define a labyrinth path for the incoming airflow.
 14. The wind power generator of claim 1, wherein the cooling system includes a plurality of fins configured to cool the hollow electric machine, said fins are connected to the nacelle along the outer surface of the nacelle at the hollow electric machine.
 15. The wind power generator of claim 14, wherein the stator includes a stator pack connected directly to the nacelle along the inner surface of the nacelle.
 16. The wind power generator of claim 1, wherein the end portion includes a cylindrical portion. 